Magnetic Actuator, Particularly for Selection Devices in Hosiery Knitting Machines or the Like

ABSTRACT

A magnetic actuator, particularly for selection devices in hosiery knitting machines or the like, comprising a main magnet, which has at least two poles arranged side by side and separated by a discontinuity, and a selection electromagnet, which is provided with at least one pole arranged in alignment with the discontinuity and spaced laterally with respect to it. The selection electromagnet can be actuated to generate or eliminate or reduce a magnetic attraction force at the pole of the selection electromagnet.

TECHNICAL FIELD

The present invention relates to a magnetic actuator particularly forselection devices in hosiery knitting machines or the like.

BACKGROUND ART

Magnetic actuators for selection devices in hosiery knitting machines orthe like are known.

Generally, these magnetic actuators are composed substantially of a mainmagnet, which has two poles arranged side by side and separated by adiscontinuity, and a selection electromagnet, which is provided with aferromagnetic core with at least one pole located at the discontinuitybetween the two poles of the main magnet. The selection electromagnet isequipped with a coil, which can be supplied with electric power in orderto eliminate or reduce substantially the magnetic attraction force ofthe pole of the core of the selection electromagnet induced by the mainmagnet.

Selection devices which use these magnetic actuators generally comprisea plurality of selection elements, made of a material which can beattracted magnetically, which can move with respect to the magneticactuator along an actuation direction and which, in their motion, facethe poles of the main magnet and of the core of the selectionelectromagnet.

The magnetic actuator is arranged on the machine so that the poles arearranged sequentially along the direction of actuation of the selectionelements so that said elements, in their motion along the actuationdirection, face in succession, with one of their sides, first one of thepoles of the main magnet and then the discontinuity and the pole of thecore of the selection electromagnet and finally the other pole of themain magnet.

Moreover, the selection elements can move from a first position, inwhich they are adjacent to, or even in contact with, said poles, to asecond position, in which they are spaced from the poles with respect tothe first position. This mobility of the selection elements in the twopositions corresponds to two different actuations of the elements of themachine, generally needles, which must be selected by means of theselection device.

In practice, in many cases the movement of the selection elements fromthe second position to the first position is contrasted by an elasticelement, which tends to keep the corresponding selection element in thesecond position. Upstream of the magnetic actuator, an abutment,constituted generally by a cam, acts on the selection elements so thatthey all reach the first position directly ahead of, or at, the firstpole of the main magnet which retains the selection elements in thisposition until the discontinuity begins. At the discontinuity, if thecoil is supplied with electric power, the attraction force of the coreof the selection electromagnet generated by the main magnet iseliminated or substantially reduced to such an extent as to beinsufficient to contrast the force of the elastic element which causesthe transfer of the selection element into the second position, in whichit remains also during transit at the second pole of the main magnet,the attraction force of which is in itself insufficient to cause thetransfer of the selection element from the second position to the firstposition. If, vice versa, the coil of the selection electromagnet is notsupplied with power, the core of the selection electromagnet retains inthe first position the selection element, which remains in this positionand is kept in said first position also during transit at the secondpole of the main magnet.

The selection element, depending on whether it is in the first positionor in the second position, consequently engaging or not other elementsof the machine, causes a different actuation of the element, generally aneedle, of the machine which is correlated thereto, achieving therequired selection.

In magnetic actuators of this kind, difficulties are observed in sizingand feeding the coil of the selection electromagnet, since in order toachieve a precise effect on the selection elements the intensity of themagnetic field induced by the electric power supply of the coil must be,at the discontinuity, i.e., at the pole of the core of electromagnet,substantially equal and opposite with respect to that of the permanentmagnetic field induced in the core of the selection electromagnet by themain magnet. If the intensity of the magnetic field induced by the powersupply of the coil is significantly lower than, or higher than, theintensity of the permanent magnetic field induced in the core of theselection electromagnet, the pole of the core of the selectionelectromagnet still applies an attraction of the selection element,obtaining an effect which is the opposite of the intended one.

The sizing and power supply of the coil of the selection electromagnetin known types of magnetic actuators are complicated, since theintensity of the magnetic field induced at the pole of the selectionelectromagnet, and therefore the attraction force applied by this poleto the selection element, varies according to the number of selectionelements which are in contact with, or adjacent to, the poles of themain magnet, since the selection elements produce, due to theirpresence, a variation of the magnetic field of the main magnet, which inturn causes variations of the magnetic field induced in the core of theselection electromagnet located inside the main magnet, at thediscontinuity, between its poles.

In known types of magnetic actuators, in order to avoid selectionerrors, it would be necessary to supply the coil of the selectionelectromagnet with a current whose intensity can vary according to thevarious selection conditions, with considerable increases as regards themanagement of the actuation of the magnetic actuators.

Moreover, magnetic actuators, in the specific application to selectiondevices, must not hinder the positioning of other elements required forthe operation of the machine. For this reason, the design of thesemagnetic actuators has always been oriented toward containing theoverall space occupation of the magnetic actuator. This goal, in knowntypes of magnetic actuators, is achieved by using small main magnets,which accordingly have a low power, with the consequence of having verysmall gaps which are comparable with the processing and assemblytolerances.

This fact forces high precision in production and assembly of magneticactuators, which increases the corresponding costs and makes itdifficult to obtain a constant behavior among magnetic actuators ofequal power.

On the other hand, in order to have larger gaps and therefore solve thisproblem, one might consider increasing the power of the main magnet, butthis, due to the way in which known types of magnetic actuators aredesigned, would force an increase in the dimensions of the coil of theselection electromagnet, generating other problems in terms of spaceoccupation of the magnetic actuator.

DISCLOSURE OF THE INVENTION

The aim of the present invention is to solve the problems describedabove by providing a magnetic actuator particularly for selectiondevices in hosiery knitting machines or the like which is simpler tomanufacture and actuate with respect to known types of magneticactuators.

Within this aim, an object of the invention is to provide a magneticactuator which is affected, to a considerably smaller extent than knowntypes of magnetic actuators, by the various selection conditions andtherefore ensures high reliability and precision in operation withoutrequiring excessive precision in the power supply and sizing of theelectrical actuation components.

Another object of the invention is to provide a magnetic actuator whichcan be provided with considerably greater dimensional and assemblytolerances than known types of magnetic actuators.

Another object of the invention is to provide a magnetic actuator whichcan utilize better the magnetic characteristics of the materials ofwhich it is made.

This aim and these and other objects, which will become better apparenthereinafter, are achieved by a magnetic actuator particularly forselection devices in hosiery knitting machines or the like, whichcomprises a main magnet which has at least two poles arranged side byside and separated by a discontinuity, characterized in that itcomprises a selection electromagnet, which is provided with at least onepole arranged in alignment with said discontinuity and spaced laterallywith respect to said discontinuity, said selection electromagnet beingactuatable to generate or eliminate or reduce a magnetic attractionforce at said pole of the selection electromagnet.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will becomebetter apparent from the description of two preferred but not exclusiveembodiments of the magnetic actuator according to the invention,illustrated by way of non-limiting example in the accompanying drawings,wherein:

FIG. 1 is a side elevation view of the magnetic actuator according tothe invention in a first embodiment, applied to a device for selectingneedles of the dial of a circular knitting machine;

FIG. 2 is a perspective view of the magnetic actuator in the firstembodiment;

FIG. 3 is a top plan view of the magnetic actuator in the firstembodiment;

FIGS. 4 to 6 illustrate an actuation sequence of a selection elementwith the magnetic actuator according to the invention in the firstembodiment shown in front view;

FIGS. 7 to 9 illustrate another actuation sequence of a selectionelement with the magnetic actuator according to the invention in thefirst embodiment in front view;

FIG. 10 is a side elevation view of the magnetic actuator according tothe invention in a second embodiment, applied to a needle selectiondevice of the dial of a circular knitting machine:

FIG. 11 is a perspective view of the magnetic actuator in its secondembodiment;

FIG. 12 is a top plan view of the magnetic actuator in its secondembodiment.

WAYS OF CARRYING OUT THE INVENTION

With reference to the cited figures, the magnetic actuator according tothe invention, generally designated in the two embodiments by thereference numerals 1 a and 1 b, comprises a main magnet 2 and aselection electromagnet 3 a, 3 b.

The main magnet 2, in both of the illustrated embodiments, has at leasttwo poles 4, 5 and 6, 7 which are arranged side by side and separated bya discontinuity 8, 9.

The selection electromagnet 3 a, 3 b is provided with at least one pole11 a, 11 b, 12 b, which is aligned with the discontinuity 8, 9 of themain magnet 2.

The selection electromagnet 3 a, 3 b comprises a permanent magnet 13 a,13 b and at least one control or actuation coil 14 a, 14 b, which can besupplied with electric power in order to reduce or eliminate themagnetic attraction force of the pole 11 a, 11 b, 12 b of the selectionelectromagnet 3 a, 3 b.

The pole 11 a, 11 b, 12 b of the selection electromagnet 3 a, 3 b isspaced laterally with respect to the discontinuity 8, 9 of the mainmagnet 2.

Conveniently, the entire selection electromagnet 3 a, 3 b is spacedlaterally with respect to the main magnet 2.

More particularly, the main magnet 2, in both of the illustratedembodiments, comprises a permanent magnet 20, which is sandwichedbetween two yokes 21, 22 which form, with their ends, two pairs ofpoles, respectively a first pair of poles 4, 5 and a second pair ofpoles 6, 7, in which the poles 4, 6 are formed by the yoke 21 and thepoles 5, 7 are formed by the yoke 22. The poles 4, 6 of the yoke 21 areseparated by a corresponding discontinuity 8 and likewise the poles 5, 7of the yoke 22 are separated by a corresponding discontinuity 9.

Each of the two yokes 21, 22 of the main magnet 2 is substantiallyU-shaped, with the discontinuity 8, 9 formed between the two free endsof the U-shape.

The permanent magnet 20 of the main magnet 2 is interposed between thetwo yokes 21, 22 proximate to the end at which the two arms of eachU-shape of the two yokes are connected.

In the first embodiment, the selection electromagnet 3 a comprises thepermanent magnet 13 a, which is connected to a yoke 25 a, which forms,with one of its ends, the pole 11 a, which is aligned with, but spacedlaterally from, the discontinuity 8, 9 of the main magnet 2.

The permanent magnet 13 a of the selection electromagnet 3 a ispreferably connected to the yoke 25 a proximate to its end which liesopposite the end that forms the pole 11 a.

The end of the yoke 25 a that forms the pole 11 a is preferably foldedtoward the main magnet 2.

The yoke 25 a is arranged laterally to the yoke 22 of the main magnet 2and the permanent magnet 13 a of the selection electromagnet 3 a isarranged at such a distance from the yoke 22 that it can use the yoke 22to close the magnetic circuit of the selection electromagnet 3 a. Inpractice, the yoke 22 is “connected”, by means of a gap 28 a, to thepermanent magnet 13 a of the selection electromagnet 3 a and acts as asecond yoke of the selection electromagnet 3 a.

Optionally, the yoke 25 a can be spaced further from the yoke 22 byapplying, to the face of the permanent magnet 13 a of the selectionelectromagnet 3 a that is directed toward the main magnet 2, aconnecting element 27 a made of ferromagnetic material, which“connects”, across or through the gap 28 a, the selection electromagnet3 a to the yoke 22 of the main magnet 2 which lies proximate to theselection electromagnet 3 a.

In the second embodiment, the selection electromagnet 3 b comprises thepermanent magnet 13 b, which is sandwiched between two yokes 29 b, 30 b,which form, with their end, the two poles 11 b, 12 b, which are alignedwith each other and with the discontinuity 8, 9 of the main magnet 2 butare spaced laterally with respect to the discontinuity 8, 9.

The two poles 11 b, 12 b of the selection electromagnet 3 b arepreferably arranged mutually side by side along a direction which issubstantially perpendicular to the direction along which the polesformed by each one of the yokes 21, 22 of the main magnet 2 are arrangedside by side.

The coil 14 b of the selection electromagnet 3 b is preferably woundaround the permanent magnet 13 b between the two yokes 29 b, 30 b.

Conveniently, in both of the embodiments of the magnetic actuatoraccording to the invention, there is a supporting element 31, made ofdiamagnetic material, which is preferably applied to the yoke 22 or 21of the main magnet 2 directed toward the selection electromagnet 3 a, 3b.

Said supporting element 31 forms a contact surface for the selectionelements which must be actuated by means of the actuator, preventingthem, despite being attracted, from making direct contact with the polesof the main magnet 2 and of the selection electromagnet 3 a, 3 b, aswill become better apparent hereinafter.

The magnetic actuator 1 a, 1 b according to the invention is designed tobe used preferably in selection devices for hosiery knitting machines orthe like, with the two poles or the two pairs of poles of the mainmagnet 2 arranged sequentially, in a substantially coplanar position,along an actuation direction, indicated by the arrow 32, so that theyface selection elements 33, made of a material that can be attractedmagnetically, which can move along said actuation direction 32 withrespect to the selection magnetic actuator 1 a, 1 b. In this manner, theselection elements 33 face sequentially a first pole or a first pair ofpoles 4, 5 of the main magnet 2, then the discontinuity 8, 9 and thepole 11 a of the selection electromagnet 3 a or the pair of poles 11 b,12 b of the selection electromagnet 3 b and then a second pole or secondpair of poles 6, 7 of the main magnet 2.

The selection elements 33 can move from a first position, in which theyare kept adjacent to the poles by the magnetic attraction applied bysaid poles, to a second position, in which they are further spaced fromthe poles with respect to the first position.

Each selection element 33, in order to pass from the first position tothe second position and vice versa, can move on a plane which isperpendicular to the actuation direction 32, and the movement from thesecond position to the first position is contrasted by an elastic means,which can be constituted by a spring 34.

Without altering the fact that the magnetic actuator according to theinvention can also be used with other types of selection devices, merelyby way of example, and only in order to clarify its actuation, theoperation of the magnetic actuator according to the invention isexplained hereinafter with reference to a device for selecting theneedles 35 of the dial 36 of a circular knitting machine, of the typedisclosed in U.S. Pat. No. 6,014,875 A by the same Applicant, which usesas selection elements 33 levers which are pivoted, about a pivoting axis37, to the end of the corresponding needle that lies opposite withrespect to the tip and can oscillate about said pivoting axis 37 inorder to pass from the first position to the second position and viceversa.

With a magnetic actuator 1 a according to the invention, in the firstembodiment, each selection element 33 is moved along the actuationdirection 32 with respect to the magnetic actuator 1 a. Before reachingthe first pole or first pair of poles 4, 5 of the main magnet 2 orthereat, an abutment, constituted for example by a cam, acts on theselection element 33, moving it from the second position to the firstposition, i.e., pushing it toward said poles 4, 5, which as aconsequence of their magnetic attraction retain said selection element33 in the first position, as shown in FIGS. 4, 7.

When the selection element 33 arrives at the discontinuity 8, 9, i.e.,it faces with another portion the pole 11 a of the selectionelectromagnet 3 a, if the coil 14 a is not supplied with power, theattraction of this pole 11 a, produced by the permanent magnet 13 a,retains the selection element 33 in the first position, as shown in FIG.5. Then the selection element 33 faces the second pole or second pair ofpoles 6, 7 of the main magnet 2 which keeps the selection element 33 inthe first position, as shown in FIG. 6.

It should be noted that the selection element 33 rests, in the firstposition, against the supporting element 31, which prevents its directcontact with the poles.

If instead the coil 14 a is powered, the attraction force of the pole 11a of the selection electromagnet 3 a is canceled out and the selectionelement 33 passes, due to the action of the spring 34, to the secondposition, i.e., moves away from the pole 11 a, as shown in FIG. 8.

Subsequently, during transit at the second pole or second pair of poles6, 7 of the main magnet 2, the selection element 33 remains in thesecond position, as illustrated in FIG. 9.

The different position assumed by the selection element 33 after itstransit at the discontinuity 8, 9 and at the pole 11 a of the selectionelectromagnet 3 a is used to engage or disengage the selection element33 with actuation elements, for example cams, in order to produce adifferent actuation of the element, which in the illustrated case isconstituted by a needle 35, to which the selection element 33 isconnected, and which is thus selected by means of the selection device.

Operation of the magnetic actuator in its second embodiment is similarto the operation described above with reference to the first embodiment,with the difference that in the first embodiment, due to the fact thatthe selection electromagnet 3 a has a single yoke 25 a, the magneticcircuit of the selection electromagnet 3 a is closed on the selectionelement 33 by using the yoke 22 of the main magnet 2, whereas in thesecond embodiment the magnetic circuit of the selection electromagnet 3b is closed on the selection element 33 exclusively by means of the twoyokes 29 b, 30 b of the selection electromagnet 3 b.

The magnetic actuator according to the invention can also be provided inother embodiments included within the scope of the protection of thepresent invention, for example by providing the selection electromagnet3 a, 3 b by means of a simple core made of ferromagnetic materialinstead of by means of a permanent magnet. Without altering the factthat the core of the selection electromagnet 3 a, 3 b can also haveother shapes, said selection electromagnet 3 a, 3 b can also be providedsubstantially as described and illustrated with reference to theaccompanying drawings, simply replacing with a core made offerromagnetic material the permanent magnet 13 a, 13 b described withreference to said drawings. Optionally, the core of the selectionelectromagnet 3 a, 3 b can be formed monolithically with the yoke 25 aor the yokes 29 b, 30 b.

In these additional embodiments, in which the selection electromagnet 3a, 3 b does not have a permanent magnet, the operation of the magneticactuator differs from the one described above in that when the selectionelement 33 is to be kept in the first position at the discontinuity 8, 9of the main magnet 2, the coil 14 a, 14 b of the selection electromagnet3 a, 3 b is powered so that an attraction force is generated at the pole11 a, 11 b, 12 c, while when the selection element 33 is to be passedfrom the first position to the second position the coil 14 a, 14 b ofthe selection electromagnet 3 a, 3 b is not powered.

In the magnetic actuator according to the invention, thanks to the factthat the pole 11 a or poles 11 b, 12 b of the selection electromagnet 3a, 3 b are spaced laterally from the discontinuity 8, 9 located betweenthe poles or pairs of poles 4, 5 and 6, 7 of the main magnet 2, theinterference of the magnetic field of the main magnet 2 on the selectionelectromagnet 3 a, 3 b is avoided or at least reduced significantly. Inthis manner, the selection electromagnet 3 a, 3 b is not affected, or atthe most is affected to a minimal extent, by the variations induced inthe magnetic field of the main magnet 2 by the different selectionconditions of the selection elements 33. For this reason, it is mucheasier to size the coil 14 a, 14 b of the selection electromagnet 3 a, 3b and determine exactly the intensity of the current for supplying thecoil 14 a, 14 b so as to cancel out or reduce or generate the attractionforce on the selection elements 33 produced by the selectionelectromagnet 3 a, 3 b.

Moreover, again thanks to this fact, in the magnetic actuator accordingto the invention it is possible to use, for the main magnet, morepowerful permanent magnets with considerably larger gaps than those ofknown types of magnetic actuators, making greater production andassembly tolerances acceptable and therefore simplifying and reducingthe cost of its production without requiring oversizing of the coil,which can maintain small dimensions.

The small dimensions of the coil and the fact that it is arrangedoutside the main magnet also allow to utilize better the space availablefor the installation of the magnetic actuator on the machine that it ismeant to serve.

Finally, it should be noted that the considerably larger gaps that arepossible with the magnetic actuator according to the invention allow themagnetic materials used to work in regions of the curve B (magneticinduction)—H (magnetizing field strength) which are linear, i.e., farfrom saturation conditions, making the actuator less sensitive to anyvariations in the supply conditions of these materials.

In practice it has been found that the magnetic actuator according tothe invention fully achieves the intended aim, since it ensures highprecision and reliability in operation and is simpler to manufacture andactuate than known types of magnetic actuators.

In the examples of embodiments described above, individualcharacteristics, given in relation to specific examples, may actually beinterchanged with other different characteristics that exist in otherexamples of embodiments.

The magnetic actuator thus conceived is susceptible of numerousmodifications and variations, all of which are within the scope of theappended claims; all the details may further be replaced with othertechnically equivalent elements.

In practice, the materials used, so long as they are compatible with thespecific use, as well as the dimensions, may be any according torequirements and to the state of the art.

Where technical features mentioned in any claim are followed byreference signs, those reference signs have been included for the solepurpose of increasing the intelligibility of the claims and accordinglysuch reference signs do not have any limiting effect on theinterpretation of each element identified by way of example by suchreference signs.

1-19. (canceled)
 20. A magnetic actuator for selection devices inhosiery knitting machines, which comprises a main magnet having at leasttwo poles arranged side by side and separated by a discontinuity,comprising a selection electromagnet, which is provided with at leastone pole arranged in alignment with said discontinuity and spacedlaterally with respect to said discontinuity, said selectionelectromagnet being actuatable to generate or eliminate or reduce amagnetic attraction force at said pole of the selection electromagnet.21. The magnetic actuator according to claim 20, wherein said selectionelectromagnet is spaced laterally with respect to said main magnet. 22.The magnetic actuator according to claim 20, wherein said selectionelectromagnet comprises a core made of ferromagnetic material whichforms, with one of its ends, said at least one pole of the selectionelectromagnet and an actuation coil which is wound around said core andcan be supplied electrically in order to generate said magneticattraction force at said at least one pole of the selectionelectromagnet.
 23. The magnetic actuator according to claim 22, whereinsaid selection electromagnet comprises a permanent magnet, which isconnected magnetically to said at least one pole in order to generatesaid magnetic attraction force at said at least one pole of theselection electromagnet, and at least one actuation coil, which can besupplied electrically in order to eliminate or reduce said magneticattraction force at said at least one pole of the selectionelectromagnet.
 24. The magnetic actuator according to claim 20, whereinsaid main magnet comprises a permanent magnet, which is sandwichedbetween two yokes which form, with their ends, two pairs of polesseparated by said discontinuity.
 25. The magnetic actuator according toclaim 24, wherein each one of said two yokes of the main magnet issubstantially U-shaped, with said discontinuity formed between the twofree ends of the U-shape.
 26. The magnetic actuator according to claim25, wherein said permanent magnet of the main magnet is interposedbetween said two yokes proximate to the region connecting the two armsof the U-shape of the two yokes.
 27. The magnetic actuator according toclaim 23, wherein said permanent magnet or said core of the selectionelectromagnet is constituted by, or is connected to, a yoke which forms,with one of its ends, said at least one pole.
 28. The magnetic actuatoraccording to claim 27, wherein said coil is arranged around said yoke ofthe selection electromagnet.
 29. The magnetic actuator according toclaim 27, wherein the permanent magnet or core of said selectionelectromagnet is spaced, by means of a gap, from the yoke of the mainmagnet that lies proximate to said selection electromagnet in order touse said yoke of the main magnet as second yoke of the selectionelectromagnet.
 30. The magnetic actuator according to claim 27,comprising an element for connecting, by means of a gap, said permanentmagnet or said core of the selection electromagnet to the yoke of themain magnet proximate to said selection electromagnet.
 31. The magneticactuator according to claim 23, wherein said permanent magnet or saidcore of the selection electromagnet is connected to two yokes whichform, with their ends, two poles which are aligned with each other andwith said discontinuity.
 32. The magnetic actuator according to claim31, wherein said two poles of the selection electromagnet are arrangedside by side along a direction which is substantially perpendicular tothe direction along which the at least two poles of said main magnet arearranged side by side.
 33. The magnetic actuator according to claim 31,wherein said coil is arranged around the permanent magnet or the core ofsaid selection electromagnet.
 34. The magnetic actuator according toclaim 20, comprising a supporting element made of diamagnetic material,which forms a contact surface for elements that can be actuated by meansof the magnetic actuator and is adapted to avoid direct contact of theactuated elements with said poles.
 35. A selection device for hosieryknitting machines, comprising a magnetic actuator as set forth in claim20, with said at least two poles of the main magnet arrangedsequentially along an actuation direction and selection elements whichcan be attracted magnetically and can move along said actuationdirection with respect to a selection actuator in order to facesequentially a first one of said poles of the main magnet, then thediscontinuity and the at least one pole of the selection electromagnetand then a second one of the at least two poles of the main magnet; theselection elements being movable from a first position, in which theyare kept adjacent to said poles by the magnetic attraction applied bysaid poles, to a second position, in which they are further spaced fromsaid poles with respect to said first position; an actuation coil ofsaid selection electromagnet being suppliable with electric power inorder to keep each selection element in said first position or allow thepassage of each selection element from said first position to saidsecond position upon its passage at said discontinuity and at said atleast one pole of the selection electromagnet.
 36. The device accordingto claim 35, wherein each selection element, in said first position,rests on said supporting element.
 37. The device according to claim 35,wherein the selection elements are movable, in order to pass from saidfirst position to said second position, on a plane which issubstantially perpendicular to said actuation direction, due to theaction of elastic means.
 38. The device according to claim 35, whereinfaces of said poles of the main magnet and of the selectionelectromagnet that are directed toward said selection elements aresubstantially coplanar.